The present disclosure relates to the field of tomosynthesis imaging and to a method and system for processing tomosynthesis imaging data for obtaining enhanced projection images.
X-ray imaging systems have become a valuable tool in medical applications such as for the diagnosis of many diseases. As standard screening for breast cancer mammography two-dimensional (2D) X-ray images are taken across the entire breast tissue. These 2D mammograms are limited by tissue superimposition. That is to say, lesions may be hidden or masked by the tissue above or below, or normal structures may mimic a lesion. In order to minimize limitations of standard 2D mammography caused by tissue superimposition, digital breast tomosynthesis (DBT) using digital detectors has been developed.
The tomosynthesis imaging systems employ at least one X-ray tube, which is moved in an arc above a stationary detector. In digital breast tomosynthesis (DBT) the volume information of an object of interest can be derived from a series of images, known as projection images or projections, which are taken at various angles by means of one or more X-ray sources. Objects of different heights in a breast display differently in the different projections. From the 2D projection images, three-dimensional (3D) volume images can be generated for review. These generated 3D volume images offer advantages to overcome the limitations associated with tissue superimposition.
During the adaption period of tomosynthesis imaging technology, the availability of 2D mammography is still desired by medical professionals and radiologists, who want to use existing expertise gained from reviewing 2D mammograms. Furthermore, archived 2D mammograms can be better compared with images obtained with the same technology than with images of a new technology, such as tomosynthesis imaging technology.
To address the need for 2D mammograms besides the availability of the relatively recently available tomosynthesis images, it is known to perform a combo acquisition of 2D images and tomosynthesis images. That is to say both 2D mammograms and DBT images are acquired for the same object of interest. However, since the average dose from tomosynthesis imaging is approximately the same as 2D mammography imaging, the radiation exposure is roughly doubled. Thus, there is the need, to generate or acquire the information of 2D mammograms without performing two image acquisitions requiring two X-ray exposures, in order to reduce X-ray dose.
One problem to be addressed is that images acquired during DBT with the use of digital detectors may be contaminated by a variety of noise sources. By noise we refer to stochastic variations as opposed to deterministic distortions such as lack of focus. One drawback is that a single tomosynthesis projection image at a given orientation or X-ray source position is very noisy because the dose per projection is not enough to be compared to a 2D mammogram acquisition. Accordingly, there is a need to improve image quality comprising noise management in order to offer a tomosynthesis 2D image that looks like a 2D mammogram in order to enable high-quality diagnostic images.
Further, there is the need to facilitate lesion identification by a health professional by providing further imaging technologies, wherein not only one 2D image but also one or more 3D images are provided. This addresses the need for possible navigation and smooth transition from 2D to 3D images.